The present invention relates to a measuring sensor device for detecting a physical magnitude which is converted by way of a physical-electrical transducer into an equivalent electrical magnitude and is then converted into magnitudes or data adapted to be further processed by an evaluation circuit, connected to the output of the sensor device, which is structurally not combined with the sensor device and is connected with the same by way of electrical lines serving for the measured value transmission and/or the energy supply of the sensor.
In measuring apparatus or measurement data acquisition and processing systems, it is frequently necessary to spatially separate the measuring sensor device with the physical-electrical transducer, properly speaking, that picks up a physical magnitude and converts the same into an electrical signal equivalent thereto, from an evaluation circuit for the signal- (respectively measured value-) preparation and processing. The sensor device and the evaluation circuit are then as a rule connected with each other by way of electrical lines, whereby the lines themselves are connected with the evaluation circuit by way of a plug-type connection.
The separation of sensor device and evaluation circuit has frequently spatial reasons (in order to be able to build the sensor device as small as possible), however, it is also frequently based on the "rough" environment in which the measurement apparatus is to be operated. They are frequently extremely high or extremely low temperatures, dirt, humidity, high electromagnetic radiation, etc., conditions under which the measuring sensor devices can operate more or less perfectly, however, the functioning ability of an evaluation circuit with sensitive electronic components is not indicated.
A measuring sensor device with a physical-electrical transducer is known from the DE 34 46 248 A1 which is not structurally combined with an evaluation circuit. The sensor device includes a memory component with correcting data for the measured values detected by the physical-electrical transducer. The physical-electrical transducer and the memory component are connected by way of at least one output with the evaluation circuit which can read out the correction data from the memory component and correspondingly correct the measured values supplied by the transducer.
However, this known sensor device and the method for its compensation merely indicate a principle or the manner of operation of such a measurement system, but provide no indication for a technical realization that can be practiced. A programming of the memory component with the correction values additionally requires a connection of a large number of lines (bus connection) which after complete manufacture of the sensor are no longer accessible from the outside so that an "aged" sensor device (i.e., a sensor device which no longer supplies correct data), can no longer be re-calibrated; it must therefore be replaced.
A sensor device with an information carrier containing operating data (memory module) is disclosed in the DE 33 18 977 A1, in which data of the memory module are read-out during start of the operation by way of several connecting lines separate from the measurement lines and are transmitted to a remotely arranged microcomputer or the entire memory module has to be fetched and transferred into a processing part operating remote from the sensor device.
Several additional lines from the sensor to the processing part or a manual operating process thus become necessary which, on the one hand, is complicated and, on the other, may frequently lead to damages of the sensitive connecting contact pins of the memory component.
It is therefore the object of the present invention to provide a measuring sensor device with a correcting data memory component, which is not combined with an evaluation circuit and is connected with the latter by way of electric lines, whereby the sensor device is constructed in a simple manner and can be manufactured in a cost-favorable manner and from which the correction data can be read-out upon start of the operation by the use of simple means.
The underlying problems are solved according to the present invention in that the memory component is a component of an answerback device integrated into the sensor device which, for the transmission of identification and characteristic data, is coupled to at least two of the first and second lines normally utilized for the measured value transmission and/or energy supply of the sensor device and is connected with the evaluation circuit by way of a further third line serving for the transmission of a clock signal from the evaluation circuit to the answerback device, whereby the clock signal serves for the synchronization of the data transmission and the current supply of the answerback device.
The advantages of the present invention reside in the first instance in that a sensor device with a correction data-memory component has been created, from which the correction data can be read-out with simple means upon start of operation of the sensor device, in that lines are used for this read-out process which are far-reachingly present already and normally serve for the measured value transmission or the energy supply of the sensor device. The circuit (answerback device) to be arranged for that purpose in the sensor device is characterized by a small number of circuit elements and influences the detection during the measurement operation in a negligible manner. The answerback device is additionally characterized by a high operating temperature range. By a slight enlargement of the answerback device additional data can be inscribed from the evaluation circuit into the memory component of the sensor device during a calibration or re-calibration by way of the existing lines.
A further advantage results with this answerback device from the possibility to be able to store and read-out operating data of the sensor device in and from the memory component because the answerback device can be operated completely independently of the sensor, properly speaking (physical-electrical transducer).